Equilibrium molecular dynamics calculation of the bulk viscosity of liquid water

• Published in: Molecular physics Vol. 99; no. 4; pp. 283 - 289
• Main Authors: GUO, GUANG-JUN, ZHANG, YI-GANG
• Format: Journal Article
• Language: English
• Published: Taylor & Francis Group 20.02.2001
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268970010011762

Twenty independent equilibrium molecular dynamics simulations were performed in NVE ensemble to calculate the bulk viscosity of water at a temperature of 303 K and a density of 0.999 gcm −3 . The energy of each simulation with a production time of 200ps was conserved within 1 part in 10 4 . By stopping the velocity-scaling procedure at a proper step, the energies of independent simulations were specified precisely. This caused the simulations of different start configurations to sample the same NVE ensemble. The shear viscosity of SPC/E water obtained in the present study was 6.5±0.4 × 10 −4 Pas, which is in close agreement with a previous calculation in the NVT ensemble (Balasubramanian, S., Mundy, C. J., and Klein, M. L., 1996, J. clzern. Phys., 105, 11 190). The bulk viscosity was 15.5 ± 1.6 × 10 −4 Pas, which is 27% smaller than the experimental value. Thus, like its behaviour in predicting the shear viscosity, the SPC/E model also underestimates the bulk viscosity of real water.